The use of optical fibres in radio astronomy

The low loss and ease of use of optical fibres for data transmission offers a number of advantages over traditional methods of bringing signals from r adio telescopes together. Aperture synthesis techniques involve the correla tion of signals from each pair of telescopes in the array. The requirements of radio astronomy systems, where the broad-band noise-like signals from e ach telescope have to be brought together coherently over distances as larg e as hundreds of km or greater in some cases, are discussed in this paper. A number of arrays around the world currently use fibres for data transmiss ion and also for the coherent transfer of local oscillator signals. Further developments in the use of optical fibres in radio astronomy are described as well as new instruments planned for the next millennium, where fibre in terconnections will be an essential part of their design.